Resistance to protein synthesis inhibitors in Coprinus cinereus

Cycloheximide, a potent eukaryotic protein synthesis inhibitor (Sisler and Siegel, 1967) was used in a biochemical and genetical investigation of the beisidiomycete fungus, Coprinus cinereus. An optimised polyuridylic acid dependant cell-free polyphenylalanine synthesising system was developed for Coprinus cinereus, in order to identify the cellular component conferring cycloheximide-resistance in two cycloheximide-resistant mutant strains, CY 8.2 and CY9.23 In both of these strains, resistance to cycloheximide was found to be associated with the cytoplasmic ribosome fraction. It was not possible to Identify the particular cytoplasmic ribosomal subunit which conferred cycloheximide-resistance. Analysis of cytoplasmic ribosomal proteins by two-dimensional gel electrophoresis did not reveaú. any difference between the small subunit proteins of CY 8 and CY 8.2. There were a considerable number of differences between the proteins extracted from the large subunit of CY 8 and CY 8.2, and CY 9 and CY9.23. There wan no conclusive evidence to identify a cytoplasmic ribosomal protein associated with cycloheximide resistance although several candidates were proposed. An analysis using carboxymethyl-cellulose chromotography did not Identify any cytoplasmic ribosomal proteins conferring cycloheximide resistance. CY 8.2 was one of 174 cycloheximide-resistant mutant strains produced by the ultraviolet mutagenesis of cycloheximide-sensitive strains, according to a method modified from North (1982). Cycloheximide- resistance in each mutant strain was considered to be conferred a single gene, which in those strains examined, was recessive in heterozygous cycloheximide-resistant dikaryons and diploids . The cycloheximide-resistance mutation in all strains examined belonged to the cy-2 complementation group (North, 1982) and hence were allelic with the resistance gene carried by CY 9.23. A classification of the cycloheximide-resistant mutants was proposed on the basis of their growth responses to cycloheximide

A polycystin-type transient receptor potential (Trp) channel that is activated by ATP.

ATP and ADP are ancient extra-cellular signalling molecules that in Dictyostelium amoebae cause rapid, transient increases in cytosolic calcium due to an influx through the plasma membrane. This response is independent of hetero-trimeric G-proteins, the putative IP3 receptor IplA and all P2X channels. We show, unexpectedly, that it is abolished in mutants of the polycystin-type transient receptor potential channel, TrpP. Responses to the chemoattractants cyclic-AMP and folic acid are unaffected in TrpP mutants. We report that the DIF morphogens, cyclic-di-GMP, GABA, glutamate and adenosine all induce strong cytoplasmic calcium responses, likewise independently of TrpP. Thus, TrpP is dedicated to purinergic signalling. ATP treatment causes cell blebbing within seconds but this does not require TrpP, implicating a separate purinergic receptor. We could detect no effect of ATP on chemotaxis and TrpP mutants grow, chemotax and develop almost normally in standard conditions. No gating ligand is known for the human homologue of TrpP, polycystin-2, which causes polycystic kidney disease. Our results now show that TrpP mediates purinergic signalling in Dictyostelium and is directly or indirectly gated by ATP.Medical Research Council (U105115237 to RRK

Investigating ‘rhomboid’ membrane proteases’ roles in development and signalling in Dictyostelium

The rhomboid family of intramembrane serine proteases is almost ubiquitous across all kingdoms of life. The enzymes are poorly conserved at sequence level but are similar in their structures and active-site motifs. They cleave disparate substrates, and it is the role of rhomboids across evolution that seems to be better conserved, since a membrane location means they are ideally placed for signalling and proteolytic activation events. Thus, we are investigating rhomboid function in the development and chemotaxis of Dictyostelium discoideum, the microbial, biomedical model organism that is capable of unicellular vegetative growth and multicellular development. A small group, including four apparently enzymatically active, rhomboids was identified in Dictyostelium. We found that development was unaltered following deletion of rhmC, whereas attempts to knock out the putative mitochondrial rhmD proved lethal. rhmA and rhmB null mutants give rise to changes in development, the lack of RhmA altering the response to chemoattractants and decreasing motility of the multicellular ‘slug’. rhmB null cells have lower viability, a smaller spore-sorus and a decreased response to folic acid stimulation. These results correspond with qRTPCR analysis, in which rhmA and rhmB transcript levels are highest during the multicellular growth phase. TEM intriguingly suggests a role in mitochondrion ultrastructure for RhmA, supported by bioinformatic interaction networks. These reveal Dictyostelium RhmA cotranscription with homologues of the Saccharomyces cerevisiae mitochondrial rhomboid’s substrates, which also regulate mitochondrial morphology

Automated Response to Query System

SMS (Short Message Service) is now a hugely popular and a very powerful business communication technology for mobile phones. In order to respond correctly to a free form factual question given a large collection of texts, one needs to understand the question at a level that allows determining some of constraints the question imposes on a possible answer. These constraints may include a semantic classification of the sought after answer and may even suggest using different strategies when looking for and verifying a candidate answer. In this paper we focus on various attempts to overcome the major contradiction: the technical limitations of the SMS standard, and the huge number of found information for a possible answer

Mobile Election

Mobile phones have the potential of fostering political mobilisation. There is a significant political power in mobile technology. Like the Internet, mobile phones facilitate communication and rapid access to information. Compared to the Internet, however, mobile phone diffusion has reached a larger proportion of the population in most countries, and thus the impact of this new medium is conceivably greater. There are now more mobile phones in the UK than there are people (averaging at 121 mobile phones for every 100 people). In this paper, the attempt to use modern mobile technology to handle the General Election, is discussed. The pre-election advertising, election day issues, including the election news and results as they come in, and answering questions via text message regarding the results of current and/or previous general elections are considered

Distinctive Features of Mobile Messages Processing

World’s mobile market pushes past 2 billion lines in 2005. Success in these competitive markets requires operational excellence with product and service innovation to improve the mobile performance. Mobile users very often prefer to send a mobile instant message or text messages rather than talking on a mobile. Well developed “written speech analysis” does not work not only with “verbal speech” but also with “mobile text messages”. The main purpose of our paper is, firstly, to highlight the problems of mobile text messages processing and, secondly, to show the possible ways of solving these problems

Instantaneous Database Access

The biggest threat to any business is a lack of timely and accurate information. Without all the facts, businesses are pressured to make critical decisions and assess risks and opportunities based largely on guesswork, sometimes resulting in financial losses and missed opportunities. The meteoric rise of Databases (DB) appears to confirm the adage that “information is power”, but the stark reality is that information is useless if one has no way to find what one needs to know. It is more accurate perhaps to state that, “the ability to find information is power”. In this paper we show how Instantaneous Database Access System (IDAS) can make a crucial difference by pulling data together and allowing users to summarise information quickly from all areas of a business organisation

Mobile Search and Advertising

Mobile advertising is a rapidly growing sector providing brands and marketing agencies the opportunity to connect with consumers beyond traditional and digital media and instead communicate directly on their mobile phones. Mobile advertising will be intrinsically linked with mobile search, which has transported from the internet to the mobile and is identified as an area of potential growth. The result of mobile searching show that as a general rule such search result exceed 160 characters; the dialog is required to deliver the relevant portion of a response to the mobile user. In this paper we focus initially on mobile search and mobile advert creation, and later the mechanism of interaction between the user’s request, the result of searching, advertising and dialog